By Kim RahnA top North Korean military official inspected the Joint Security Area (JSA) through which a North Korean soldier defected to South Korea almost three weeks ago, according to government sources, Sunday.The inspection by Ri Myong-su, chief of the general staff of the Korean People's Army and one of the closest military aides to North Korean leader Kim Jong-un, indicates the North Korean leadership takes the defection very seriously, and is taking measures to reinforce guards at the border.According to sources, Ri visited the North's side of the JSA about 10 days after the defection."It is unusual for the chief of the general staff, who is one of the highest ranking officials in the country, to inspect an area where a defection was made," a source said.Following the incident, North Korea already replaced all border guards there ― between 35 and 40 soldiers. It is also presumed commanders and other senior officials of the guard unit have been punished for failing to prevent the soldier's defection. North Korea has also been building a checkpoint, a gate and a concrete protective wall on the so-called 72-Hour Bridge across which the soldier drove a military jeep toward the JSA.The source also said the North has been replacing all soldiers at its guard posts (GPs) in the Demilitarized Zone (DMZ) since the end of November. "To prevent a similar defection at the JSA, North Korea is likely to become more careful in selecting soldiers to be deployed to the GPs by strictly assessing their family backgrounds," the source said.Those deployed to the JSA also used to be children of the elite who are loyal to the ruling Workers' Party of Korea.The soldier who defected to South Korea was wounded by multiple gunshots from North Korean soldiers during the defection. He underwent multiple surgeries and is recovering at a hospital in Suwon, Gyeonggi Province.